This invention relates to improvements in machines for sharpening saw chains, and particularly to a machine for sharpening the cutters of a saw chain while the chain remains installed on the chain saw bar.
In the interest of saving time which would otherwise be spent in removal, reinstallation, and adjustment of a saw chain, it is very desirable to be able to sharpen such a saw chain while it remains installed on the bar of the chain saw. It is additionally desirable to be able to sharpen the saw chain at the site where the saw is being used, rather than to have to transport the chain saw to a remote location for sharpening.
While there are devices available which permit a saw chain to be sharpened while installed on the bar of a chain saw, the previously known devices include certain disadvantages which need to be overcome. For example, the chain saw sharpener disclosed in Silvey U.S. Pat. No. 3,877,324 comprises a large supporting stand which supports a grinder wheel as well as a pivoted support table and a saw bar clamp which hold the entire chain saw. The entire chain saw itself must be moved relative to the stand and grinder wheel, to shift from a position for sharpening cutters of one hand to a position for sharpening cutters of the other hand. Because of this heavy stand, and the pivoted table and saw bar clamp, the size of the apparatus reduces the practicality of its use to sharpen chain saws except in a shop.
Simington U.S. Pat. No. 4,104,793 discloses a portable saw chain sharpener which clamps to the bar of the chain saw, and therefore does not require the entire chain saw to be moved in adjusting from grinding left-hand to right-hand cutters. The manner of adjusting the Simington chain saw sharpener, however, is somewhat complex, since the device provides no direct indications of the angles to which cutter edges are ground.
What is needed therefore is a saw chain sharpener which is easily portable, permitting use in remote locations, and in which independent adjustments directly provide desired changes of cutter shapes without unnecessary interrelationship of the results of the various adjustments.